1. Field of the Invention
This invention relates to a wavelength multiplexed optical fiber transmission system, and a dichroic beamsplitter therefor. Accordingly, it is a general object of this invention to provide a new and improved system and splitter of such character.
2. Description of the Prior Art
Dichroic beamsplitter optical wavelength multiplexers, in the past, have been considered practical for only widely separated wavelengths, such as, for example, 0.85 .mu.m and 1.06 .mu.m, due to the unavailability of beamsplitters that operate efficiently for smaller wavelength separation.
At least one report, including one by W. J. Tomlinson, Applied Optics 16, p. 2180 (1977), has concluded that dichroic beamsplitters are impractical for wavelength multiplexing in an optical system because their characteristics are strongly polarization dependent.
K. Aoyama and J. Minowa, Applied Optics 18, p. 2834 (1979), and Tomlinson in the cited Applied Optics 16 article have concluded that the optimum manner for achieving optical wavelength multiplexing is through the use of blazed diffraction gratings. A wavelength multiplexer was reported by Aoyama and Minowa, in the Applied Optics 18 article, which utilizes a grating technique for achieving a 200 .ANG. interchannel wavelength spacing.